It is strange, as on my Firefox they were about the same size. I think that before they were using the default font of the OS (so rather random from one PC to another), but now they use the same font as the rest of the page.
All texts have exactly the same size, plain text and fields.

I'll try to slightly increase the size of the box around the fields to make all a little nicer, but the text of the fields has no reason to be bigger than the rest. Or if you want a bigger text in overall, there is the new option 'Larger text' in the profile. Maybe I'll slightly increase the overall size of everything and put an option to define a custom zoom like for the admin pages.

I'll contact via private message you tomorrow so you can check on an old copy of the site (similar to the test site), if you can make a screen capture, so I can try to understand better what exactly you miss from the old version